1. Field of the Invention
The present invention relates to a method of producing a carrier on which a substance, a biological material such as a protein in particular, can be immobilized stably while retaining its activity.
2. Background Art
The technology of immobilizing biomolecules is used in various applications such as biochips, biosensors, affinity carriers, μTAS, cell culture substrates, etc, and numerous variations thereof are known. One that is drawing particular attention is the method of immobilizing biomolecules through a hydrophilic spacer such as polyethyleneglycol (PEG). A hydrophilic spacer has several excellent effects, which include a reduced rate of deactivation of the biomolecule due to the immobilization, improvement in the mobility of the immobilized biomolecules, suppression of nonspecific adsorption of non-target molecules, and promotion of interactions between biomolecules. However, the hydroxyl groups originally present in PEG have low reactivity and it is therefore generally difficult to form covalent bonds between the PEG and the support surface, or to bind the biomolecule to the free ends of the PEG under physiological conditions. For these reasons, usually, a PEG derivative that has a functional group that is more reactive than the hydroxyl group is used as the hydrophilic spacer.
For example, in JP Patent Publication (Kokai) No. 07-59567A (1995) and Analytical Chemistry, 77, 1096-1105 (2005), PEG derivatives having amino groups at both ends are used as the hydrophilic spacer. In Specification of U.S. Pat. No. 6,033,784, a PEG derivative with a quinone component at one end and an electrophilic functional group at the other end is used as the hydrophilic spacer. A PEG derivative with biotin at one end and an active ester at the other end is used in Proceedings of the National Academy of Sciences, 98, 852-857 (2001). In Langmuir, 15, 7186-7198 (1999), a PEG derivative having a carboxyl group at one end and an alkane thiol at the other end is used. All these documents in the public domain claim that hydrophilic spacers give many excellent effects such as maintenance of the activity of the immobilized biomolecules, improvement of conformational mobility of the immobilized biomolecules, and suppression of nonspecific adsorption of non-target molecules.